Controlled formation of 3D functional structures is a topic of broad and increasing interest, particularly in the last decade, due to important envisioned uses in nearly every type of micro/nanosystem technology, from biomedical devices to microelectromechanical components, metamaterials, sensors, electronics and others. Although volumetric optical exposures, colloidal self-assembly, residual stress induced bending and bio-templated growth can be used to realize certain classes of structures in certain types of materials, techniques that rely on rastering of fluid nozzles or focused beams of light, ions or electrons provide the greatest versatility in design. Applicability of these latter methods, however, only extends directly to materials that can be formulated as inks or patterned by exposure to light/energetic particles, and indirectly to those that can be deposited onto or into sacrificial 3D structures formed with these materials. Integration of more than one type of any material into a single structure can be challenging. Furthermore, the serial nature of these processes sets practical constraints on operating speeds and overall addressable areas. In addition, of the many methods for fabricating such structures, few are compatible with the highest performance classes of electronic materials, such as monocrystalline inorganic semiconductors, and only a subset of these can operate at high speeds, across length scales, from centimeters to nanometers.
Origami and Kirigami are now topics of rapidly growing interest in the scientific and engineering research communities, due to their potential or use in a broad range of applications, from self-folding microelectronics, deformable batteries, and reconfigurable metamaterials, to artificial DNA constructs. Important recent advances in the fundamental aspects of origami include the identification of mechanisms for bi-stability in deformed configurations, and the development of lattice Kirigami (a variant of origami that involves both cutting and folding) methods that solve the inverse problem of folding a flat plate into a complex targeted 3D configuration. In parallel, experimental methods are emerging for the assembly of origami structures at the micro/nanoscale. For example, a representative class of approaches relies on self-actuating materials, such as shape memory alloys, shape memory polymers, liquid crystal elastomers, and hydrogels, for programmable shape changes. These schemes are, however, not directly applicable to many technologically important types of materials, such as semiconductors or metals. Other routes rely on capillary forces (or surface tension forces), or residual stresses in thin films to drive the origami assembly, with the distinct practical advantage of compatibility with established planar device technologies. In most cases, however, such approaches are irreversible and offer limited control of parameters such as the folding angle, or folding rate.
From the foregoing, it will be appreciated that methods and design parameters for forming complex three-dimensional structures that exploit the existing base of competencies, in which spatially controlled compressive buckling induces rapid, reversible, large area geometric extension of 2D precursors into the third dimension, would be beneficial for various applications.